If you compare you got to count Fast Memory on the 1200, because it was standard, all people had it. Many games and programs would not work without it. When added, the CPU MIPS goes from 2x an Amiga 500 to about 5x an Amiga 500. It was less than 100 bucks, and it added the missing RTC to. The same goes for RAM expansion in A500 and A1000 too, the games required it and it was less than 100 bucks.
The AGA has broader bandwith, allowing for hardware scrolling of hires, hires sprites and so on. It has 24 bit - 16,8 mill color palette (A030 has 18 bit), The co-processors has nothing to do directly with 3D, but it takes the CPU load off for the other things when displaying 3D, so the CPU only has to do the 3D. Using "Chunky" on the F030 for example will make little CPU left for the 3D calculations. Amiga is like Atari ST series, 2D platforms. Back then, you need a Silicon Graphics workstation or a SGI Mini or something to get good realtime 3D.
When it comes to making professional 3D, Amiga 3000 and 4000 was sold bundled with Video Toaster systems as Video Toaster Amiga, that hardware included special processor for faster 3D rendering, Lightwave, and also supported multiple Amigas as render farms. This 3D system was used for creating first seasons of Babylon 5 on TV, special effects for Robocop movie, like the rpg missils, Seaquest movie etc.
On Amiga you also get RTG cards with real 3D hardware and Open GL support, like with Cybervision 64.
Capture source looks like emulator to me...no doubt ran with an emulated 50Mhz 030
I just tested this demo on my own A1200, it ran silk smooth, just like the YouTube one.